Several things could cause this. There could be a leak in the pressure system that is allowing freon to escape. The compressor could be failing to generate enough pressure to drop the gas temperature. There could be a hole in the duct that allows colder air to escape before it reaches the vent. It could also be that the duct is poorly insulated and the air is rewarmed before it reaches you.
Adding freon to an air conditioning unit should only be done by a certified technician. It is in fact illegal for anyone to add freon to air conditioning that isn't properly certified, so one would add freon by calling in a certified technician to do it for them.
Freon is odorless, non-flammable, and is not corrosive. It is unlikely that's the source of your discomfort. Moreover, if your central air unit sprang a leak, it wouldn't take long for the freon to discharge completely. Your unit will no longer being cooling. If it's still cooling, even inefficiently, it's definitely not the freon.
in the air conditioning unit
A complex machine such as an air conditioner can fail in many different ways, but the most usual way is a leak of the coolant (which is probably freon).
Low freon charge? Heater cable not fully in cool position?
where do I add freon to my air conditioning unit on a 1997 chevy truck?
it will break the unit
nowhere
where is low side charge port located
Never, unless you have a leak.
3
The operating principle of air handling unit is by circulating and then conditioning air flow. This is achieved by cooling, heating and ventilating the units.